1. Field of the Invention
The present invention relates to an image reading apparatus used in a copier, a scanner, a fax machine, or the like. More particularly, the present invention relates to an improvement to a jam clearance mechanism that relieves a paper jam occurring in an automatic document feeder (hereinafter called “ADF”) provided in a platen cover.
2. Description of the Related Art
A known jam clearance mechanism of this type is presented in, for example, Laid-open Japanese Patent Application Publication No. 2002-220146 (see, in particular, paragraph [0033] and FIG. 5). In Laid-open Japanese Patent Application Publication No. 2002-220146, a paper ejection guide is pushed downward against a force of a spring by raising a paper feeding tray from a normal horizontal orientation to an upright orientation. As a result, an idle paper ejecting roller provided on the paper ejection guide separates from a driving paper ejecting roller, making it easier to remove a document. An eccentric cam for pushing the paper ejection guide downward is provided near a swinging center of the paper feeding tray.
Laid-open Japanese Patent Application Publication No. 2004-136999 discloses a similar jam clearance mechanism. In a jam clearance mechanism according to Laid-open Japanese Patent Application Publication No. 2004-136999 (see, in particular paragraphs [0041] and [0042], and FIG. 1), a movement occurring when opening a cover of an upper portion of an ADF is conveyed to a releasing lever by another lever and causes a separation pad arranged to rock in tandem with the releasing cover to separate from a circumferential surface of a separation roller, thereby making it easier to remove a document.
There is another known jam clearance mechanism for clearing a paper jam in a fusing section of a copier. In this jam clearance mechanism, a special paper ejection dial is provided in a recording paper document feeding route and a recording paper is removed by turning the paper ejection dial (Laid-open Japanese Patent Application Publication No. 2002-278332 (see, in particular, paragraph [0019] and FIG. 5)).
With the jam clearance mechanisms disclosed in Laid-open Japanese Patent Application Publication No. 2002-220146 and Laid-open Japanese Patent Application Publication No. 2004-136999, a document is rendered easier to remove by manipulating a paper feed tray to an upright orientation such that a pair of paper ejecting rollers separate from each other or by opening a cover such that a separation pad and a separation roller separate from each other.
However, with the jam clearance mechanism of Laid-open Japanese Patent Application Publication No. 2002-220146, a pair of paper ejecting rollers provided at a finishing end of a document feeding route are merely separated from each other. Similarly, with the jam clearance mechanism of Laid-open Japanese Patent Application Publication No. 2004-136999, a separation pad and a separation roller provided at starting end of a document feeding route are merely separated from each other.
In many cases, a document feeding route of an ADF is configured to have a U-shaped configuration such that a paper supply port and a paper ejection port can be provided on the same side surface and a plurality of pairs of feeding rollers are provided along the document feeding route. Consequently, if a paper jam occurs in an intermediate portion of the document feeding route, the document cannot be ejected by using the jam clearance mechanism according to Laid-open Japanese Patent Application Publication No. 2002-220146 or Laid-open Japanese Patent Application Publication No. 2004-136999. In such a case, it is necessary to provide a jam clearance mechanism that can accommodate a paper jam occurring in an intermediate portion of the document feeding route, but this is not easy to accomplish.
With the jam clearance mechanism of Laid-open Japanese Patent Application Publication No. 2002-278332, a paper jam occurring in an intermediate portion of the document feeding route may be cleared by turning the paper ejection dial and removing the recording paper. However, it is necessary to perform tasks such as opening a cover or opening a drawer of a case of a fusing unit before the paper ejection dial can be operated. The series of tasks required to eject the paper takes effort and becomes troublesome to a user. Moreover, although the series of tasks for ejecting a jammed piece of paper needs to be executed in a prescribed order, there are cases in which a user neglects the order and attempts to forcefully remove a jammed sheet of recording paper or a document, thereby causing damage to the paper.